In a first for Hong Kong, the Integrated Centre for Wellbeing (I-WELL) of The Education University of Hong Kong (EdUHK) has adopted an eye-tracking technique for use in its assessment of the effectiveness of drug rehabilitation. Whatever catches the participants’ attention, whether they look at a particular picture repeatedly or whether their gaze fixes on something, is recorded and used to identify hidden addiction, if any, more scientifically.
Professor Leung Chi-hung, Co-Director of I-WELL and Professor (Practice) of Department of Special Education and Counselling, EdUHK, has led his team to conduct a series of integrated tests employing eye-tracking techniques. The first application was a study to assess the ability of children with Autism Spectrum Disorder to associate various kinds of emotions with corresponding facial expressions. More recently, Cheer Lutheran Centre appointed EdUHK to conduct a three-year study to evaluate the effectiveness of a drug treatment program for youngsters. EdUHK researchers formulated a series of tests that included eye-tracking to complement conventional methods. Professor Leung believes the technique reveals youngsters’ proclivity towards drugs, but it shows more respect for their dignity, in contrast to substance abuse tests done with collected hair or urine.
Delayed judgment amid dilemmas
The objective of the research is not just to identify hidden addiction among the participants, but also to detect any tendency of a relapse. The first phase of the eye-tracking research involved 92 people, who had to regularly complete quizzes. They were split into four groups: university students who had never taken drugs, participants in Cheer Lutheran Centre’s half-year drug treatment program, people who had just started quitting drugs, and drug addicts.
A pre-installed eye-tracker in the Centre’s computer collects the eye-tracking data during the quiz. Two photos are shown side by side on the computer screen at a time, one related to drugs and another not: for example, a pile of pills versus a pile of marshmallows, or an injection versus acupuncture. Every picture is shown to the participant for half a second to one second. After the quiz, the participant undergoes further quizzes on colors and responses.
Professor Leung explained that humans are naturally attracted to objects that bring pleasure and excitement. Research studies have shown that drug addicts subconsciously look at drug-related pictures first and their gazes last longer. Their eyes are also drawn repeatedly to those images. The eyes of those who have started the process of quitting drugs look at the space in between the two pictures, indicating an inner struggle. In many cases, the probability of resuming drug use peaks a month after the person begins to quit. During this stage, the participants are stimulated by drug-related pictures, so hidden drug addiction can be spotted through eye-tracking.
The research also tests the responses of participants. Those who have just started quitting drugs usually find it harder to associate drug-addiction with negative phrases, since they still find drugs appealing. Similarly, their speed of response is slower, as they face a dilemma. Hence, the response rate helps reveal their tendency to return to drug use. To complete the series of tests, the participants need to fill in a traditional questionnaire.
Accuracy rate reaches 95%
The study, which has been operating for only a year and a half, is already showing results. Professor Leung mentioned that a questionnaire is an explicit way of doing research, so the participants can figure out the objective of the questions and it is not unusual for them to conceal their genuine thoughts when answering the questions. In contrast, eye-tracking, is an implicit form of research, allowing the most spontaneous responses of the participants to be captured.
He added that situational factors might also affect thinking ability. For example, participants who get sick on the test day respond more slowly across the board. The eye-tracking technique becomes a more reliable tool in this instance, as eye-tracking data records less variation, giving an accuracy rate as high as 95%. Since nearly 80 sets of pictures are shown randomly, the accuracy rate is not affected even if the participants take the tests repeatedly. Professor Leung believes that the eye-tracking technique can also be applied to studies of other forms of addiction, such as gambling, and promiscuous behavior.